Carpal tunnel syndrome results from compression of which nerve?

• A. Median nerve
• B. Ulnar nerve
• C. Radial nerve
• D. Sciatic nerve

Answer: (A)

Carpal tunnel syndrome occurs when the median nerve is compressed as it passes through the carpal tunnel of the wrist. The tunnel is formed by carpal bones and the transverse carpal ligament, and it also contains flexor tendons. When the median nerve is squeezed, you get numbness, tingling, or weakness in the thumb, index, middle, and the radial half of the ring finger, often with trouble in thumb opposition due to thenar muscle weakness. The other nerves don’t fit this pattern: the ulnar nerve affects the little finger and part of the ring finger and intrinsic hand muscles in a different distribution; the radial nerve relates to the back of the hand and wrist extension; the sciatic nerve is in the leg. So the nerve being compressed in this condition is the median nerve.